Maybe Scott Adams said it best:

To put it bluntly, goals are for losers. That’s literally true most of the time. For example, if your goal is to lose ten pounds, you will spend every moment until you reach the goal—if you reach it at all—feeling as if you were short of your goal. In other words, goal-oriented people exist in a state of nearly con

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Deferred Happiness Syndrome:

The common feeling that your life hasn't begun, that your present reality is a mere prelude to some idyllic future. This idyll is a mirage that'll fade as you approach, revealing that the prelude you rushed through was in fact the one to your death.

Note that seeking happiness as an end might be counterproductive. Many people report that constantly checking to see if they are happy actually decreases their happiness - a report that fits with the research on "flow." It may be better to seek some of the above goals as ends, and happiness will be a side-effect.